Well packer



R. P. VINCENT WELL PACKER April 15, 1958 Filed Sept. 14 1950 2 Sheets-Sheet 1 FIG.-- 2

RENIC P. VINCENT IN V EN TOR.

ATTORNEY Unit States Patent WELL PACKER Renic P. Vincent, Tuisa, Okla, assignor to Pan American Petroleum Corporation, a corporation of Delaware Application September 14, 1950, Serial No. 184,854

Claims. (Cl. 103-52) This invention pertains to well packers, particularly to resettable packers, such as formation packers, in which the packing element is distended a great amount when the packer is set in a well.

Packing elements of. well packers have been constructed along two general lines. There is, first, the elastic solid cylindrical packing element which has a high Poissons ratio and is swelled by pressure on the ends to plug or seal a well. Such elements are typically made from neoprene. This type of packer is preferred in most cases, and particularly in permanent settings. It it not recommended for use where more than about 10% expansion is required. The other class of well packer is the inflatable type, in which the packing element is expanded diametrically by fluid pressure. This class is sometimes used where pressure differentials across the packer are relatively small, for example, in shallow wells. Inflatable packer elements are adapted to expand up to about 1 /2 times their initial diameter provided the differential pressure across the packer is not too great. Generally, however, the packing element has to be constructed too thick to be expanded to more than about 1%. times'the initial diameter of the inflatable element. Even where the walls of a hydraulic packing element are relatively thick, they occasionaly rupture or leak and cannot be used as a permanent installation.

It is an object of this invention to provide an improved well packer. A further object of this invention is to provide a well packer of the solid type which is adapted to expand to two or more times its initial diameter. A still more specific object of this invention is to provide an improved well packer which may be reciprocated automatically in a well tubing to lift well fluids to the surface. Other objects of this invention will become apparent as the description thereof proceeds. In this description, reference will he made to the accompanying drawings in which:

.Figure 1 is a cross-sectional view of a well packer in a retracted position;

Figure 2 is a cross-sectional view of the well packer shown in Figure 1 with the packing element expanded;

Figure 3 is a view, partly in cross section, of a well packer, in a retracted position, which is adapted to be expanded in a well by the application of a static pressure on the packer; and

Figure 4 is a cross-sectional view of a preferred embodiment of a well packer of the type shown in Figure 3 which is particularly adapted to reciprocation in a well tubing to lift Well fluids.

Referring now to the drawing in which like numerals designate the same parts in the various figures, my packer, as shown in Figure 1, consists generally of a packer body 10, a mandrel 11, a packing element 12, and means simultaneously to compress and twist the packing element. The packer body may be attached, as by threads 13, to the tubing (not shown) on which the packer is lowered into a well. The upper end of the packing element is driven onto the packer element adapter 14, which may be unitary with the packer body as shown. That end of the packer element is then clamped to the packer body as by a clamp 15 which is slipped over the body 10 until it contacts shoulder 16. The sharpened points 17 of the clamp are then driven into the end of the packing element 12, connecting that element to the body. The lower end of the packing element is similarly clamped to a collar 18 which has a shoulder 19 larger than the inside diameter of the clamp. Collar 18 may be connected, as by'threads 21' to the lower end of mandrel 11. The mandrel is screwed through the collar a sutficient distance to be connected, as by threads 21, to an anchor or a spade (not shown). Packer anchors, as is well known, may be fixed to the casing in a well; or particularly in the case of formation packers the anchor may consist of a pipe which extends to and rests on the bottom of the well. As pointed out hereinafter, my packer is usually set by the application of a torsional force; and, therefore, in the case of the open-hole packer the anchor preferably has a spade or other means at the bottom to prevent the anchor from rotating as the packer is set.

A follower pin 22 is inserted through a tapped hole 23 in the body into a hole drilled through the upper end of mandrel 11. The hole 23 may be plugged to prevent the pin from falling out of position. Pin 22 is longer than the inside diameter of body 10, the ends fitting into cams 24-, of which only one is shown. These cams permit packer body 10 to be rotated with respect to mandrel 11; and, as the body is thus rotated, the two are telescoped or drawn together, thereby compressing and twisting packer element 12.

Packer element 12 consists of a sleeve of resilient material, such as rubber or rubber-impregnated fabric. The rubber and fabric are desirably resistant to decomposition or disintegration by fluids, such as oil, with which they come into contact in a well. For this reason, the packer element is usually made of a synthetic rubber, such as neoprene, Thiokol, or the like. This sleeve has one or more spiral cuts 25 in the center portion, as indicated. While the packing element may be constructed from a series of spirally wrapped strips with the ends joined, I generally take a solid sleeve and make a number of spiral cuts throughout the center portion thereof leaving uncut tubular ends 26. The pitch of these cuts may be from about /2 to 5 times the outside diameter of the sleeve or more, depending upon the number of starts, i. e., the number of parallel cuts which are made. The number of starts depends upon the diameter of the packer element. In a small packer element, such as might be used in a 1" diameter tubing or less, one start is generally sufficient. In a 2 packer element, two or three starts are preferred. In larger packers, as many as 5 or more starts may sometimes be desirable to prevent the packing element from being too rigid. In any case, however, I have found it desirable to make the angle of the cut, i. e., the pitch divided by the circumference, less than the angle of the cams 24 so that as the diameter of the packing element is expanded by twisting it is also compressed axially and as the diameter is retracted the packing element is stretched axially to reduce the outside diameter. The length of the packing element may be varied over a substantial range. I have found, however, that the minimum length is desirably about two times the outside diameter or greater. In a formation or open hole packer the outside diameter is desirably as large as will pass through the smallest obstruction in a well to get to the position where a pack-off is desired. The inside diameter of the packer element is preferably as small as the construction of the mandrel will permit, so that the thickness is as great as possible. In any case, the thickness is desirably greater than about one-half of the difference between the radius of the hole which is to be plugged and the radius of the mandrel 11 so that, when the packer is set or expanded, the separate strips can not bypass one another.

Referring now to Figure 2, the spirally cut packing element 12 is expanded by anchoring the lower end of mandrel 11 as described above and rotating the packer body with the tubing which is connected to threads 13. The packer element may be expanded by rotation of the tubing in either direction, depending upon the angle of the cams 24 and the angle of the cuts 25. Where the cams and the cuts progress like a right-hand thread, the tubing and the packer body are turned clockwise at the surface, telescoping the mandrel and body and twisting the packing element by exerting a force on the ends of the strips parallel to the cut to expand the packer element. In some cases where the angle of the earns 2 is greater than about 15, the packer may be expanded by merely releasing the weight of the tubing at the surface so that the ends of pin 22 will slide around the cams 24 and twist the packing element and the tubing. Where the pitch of the spiral cuts is greater than about 30, pin 22 and earns 24 sometimes are unnecessary, since the weight of the tubing causes it to rotate and twist the packer element. The diameter of the packer element may be retracted in any case by merely lifting the tubing.

This packer is particularly suited to use as a formation packer due to the ability of a spirally cut packer element to expand more than a solid sleeve. It may also be used to advantage when the packer element seats on a smooth surface, for example, to plug casing or tubing or to plug the annulus between the tubing and the easing in a well. The packer element also, due to its ability to expand and withstand extreme wear, may be used to advantage as pump packing or the like.

An embodiment of my packer which is adapted to being seated in a well by the application of an atmosphere of high fluid pressure is shown in Figure 3. This embodiment, as shown hereinafter, may also be employed as a gas-lift plunger for gas-lifting fluid from a well. The packer consists essentially of an upper section or body 31, a lower section or mandrel 32, and a spirally cut packing element 12. The body is closed at the upper end by a head which may contain a valve 33. As pointed out hereinafter, the chamber 34 in body 31 is prepressured prior to inserting the packer into the well by injecting a compressible fluid, such as air, through valve 33. Valve 33 may, therefore, be a core valve of the type employed in pneumatic automobile tires. The mandrel 32, which may be of solid or tubular construction, forms a piston in body 31 and encloses variable volume chamber 34. The packer element is connected at the top to body 31 and at the bottom to mandrel 32 by clamps 15. The top connection is preferably through packing gland 35. Packing 36 provides a fluid seal between the bore 37 of body 31 and mandrel 32 to keep well fluids out of chamber 34. A spiral cam 38 is cut in the mandrel 32, preferably near the top. Plug 39, which is screwed into body 31, extends into this spiral cam. Upper guides 41 may be attached to body 31, as by welding a number of lugs or spring elements thereto. Similarly, lower guides 42 consisting of a number of solid lugs or spring elements may be welded or otherwise attached to the lower end of mandrel 32. These guides tend to keep the packer centered in the tubing to prevent unnecessary wear on the outside surface of packing element 12 as the packer is lowered into a well.

In operation, chamber 34 is prepressured with air or some other gas. Hydrostatic pressure on the ends of the packer tends to force mandrel 32 into chamber 34, compressing and twisting the packer element 12. The amount of pressure required to expand this packer element depends upon the pressure of the gas in chamber 34. Therefore, the chamber is prepressured to any amount, depending upon the well pressure atwhich it is desired to set the packer. The packer is placed in the well either on a tubing, a wire line, or the like, or it may be dropped into the well in this condition. The packing element will be expanded as the packer is lowered through the liquid in the well; or, when the packer is in position in the well, fiuid may be injected into the well to build up a static pressure great enough to compress the packer. As the packer is compressed by fluid pressure at the ends, mandrel 32 is rotated with respect to packer body 31, diametrically expanding and axially compressing packing element 12. A preferred method of setting the packer is to lower it on a wire line and, after it is spotted, to build up a hydrostatic head on the packer by the injection of fluid into the well. Slips may be actuated by the expansion of the packing element to anchor the packer in a pipe. In open hole slips are unnecessary. The packer remains expanded as long as the static head thereon remains above the expansion pressure as controlled by the prepressuring of chamber 34. The packer may be withdrawn by decreasing the pressure head on the packer, as, for example, by pumping the liquid out of the well above the packer.

This embodiment of my packer is particularly adapted to use as a gas-lift plunger. In co-pending joint application, S. N. 158,836, filed April 28, 1950, now U. S. Patent 2,688,928, a gas-lift system employing a pressureactuated gas-lift plunger is described. This pressureactuated packer may be substituted in that system for the gas-lift plunger therein described. The present packer has an advantage in many cases over the packer therein described in that the packing element being spirally cut expands to a substantially greater degree than the solid packer. This has particular advantage in a gas-lift system of the type described, since the clearance between the packer and the tubing can be increased, thereby allowing the packer to fall through the tubing at a greater rate than a packer which employs a solid packing element.

An alternative embodiment of a pressure-actuated well packer is shown in Figure 4. While this embodiment, like the embodiment shown in Figure 3, is particularly adapted to use as a plunger in a gas-lift system of the type described above, it is also adapted to plugging or packing ofl? a well when the static pressure on the packer is increased to a predetermined pressure.

The packer consists essentially of packer element 12 and a cylindrical packer body 51 which slides over mandrel 52. A top guide 53, which includes a valve 54, a fishing neck 55, guide vanes 56, and wiper 57, is attached to the top of the packer body as by threads 53. The valve 54 seats in the top of mandrel 52 when the mandrel is raised to compress axially and expand diametrically the packing element 12. A ring 59 is pressed into a recess 61 in the top guide 53 to hold wiper 57 which may be felt or the like. When the top guide 53 is completely made up in packer body 51, a space 62 is left between ring 59 and shoulder 63. A snap ring 64, which has a diameter in an unstressed state less than the outside diameter of mandrel 52, is placed in this space and expanded around mandrel 52. This snap ring fits into an annular recess 65 in mandrel 52, thereby tending to hold the mandrel in a certain position with respect to the packer body until the force tending to move the mandrel in the body becomes greater than the force exerted by the snap ring. In addition to the wiper 57, above described, which is generally for the purpose of keeping solid foreign particles from between the mandrel and the small bore of the body, a fluid seal such as a bellows, a packing gland 66, or the like is provided in the space between the minor bore of the packer body and the mandrel.

A pin 22, having a length greater than the diameter of mandrel 52, is inserted into the top of the mandrel through a tapped hole 23 in the packer body. The ends of this pin extend into spiral earns 24 which are oppositely disposed in body 51. A compression spring 67 resting against shoulder 68 between the major bore and the minor bore of the packer body urges piston 69 on mandrel 52 down keeping the packing element in a retracted position when the packer is not under pressure. This spring operates in the major bore of the packer body within an annular chamber 71, which is either evacuated or filled with a compressible fluid, such as air. This chamber is in some cases prepressured with air so that a spring is unnecessary. An O-ring 72 seals the lower end of this chamber between the piston and the major bore of the packer body. The piston 69 strikes lower cylinder head 73, which is connected as by threads 74 to the lower end of valve body 51, when the packing element is in a totally axially extended or diametrically retracted state. An upper packing element adapter 75 having a shoulder 76 and a clamp 77, connects the packing element 12 to the lower cylinder head '73. A lower packing element adapter 78, having a shoulder 79, a clamp 77, and a pin 80, connects the bottom of packing element 12 to mandrel 52. This connection is flexible inasmuch as pin 80 fits loosely in slots 81 cut in mandrel 52. Lower packing element adapter 78 is urged upwardly by compression spring 82 placed between this adapter and bottom guide 83. The bottom guide consists of a body 84 which is connected, as by a pin 85 to the lower end of mandrel 52 and of guide vanes 86, which center the packer in the tubing and prevent wear of the packing element when it is in a retracted position as it falls in the well.

In operation this embodiment of my packer is extended axially, as shown in Figure 4, so that snap ring 64 is in recess 65. The packer is dropped into the tubing in this extended state. It falls through the tubing due to its own weight until it contacts a bottom stop in the tubing or until the hydrostatic head of fluid above the packer is great enough, acting on the bottom of piston 69, to expand snap ring 64 and move mandrel 52 up in body 51 into seating engagement with and closing valve 54 on the top of the mandrel and compressing or diametrically expanding packer element 12. The hydrostatic fluid head above the packer is applied to piston 69 as the well fluids flow through the unpacked annulus between the mandrel and the upper packing element adapter 75. As the mandrel thus moves up in the body, follower pin 22 moving in spiral cams 24 causes the lower end of packing element 12 to be rotated with respect to the top end of that element, thereby unwinding the packer element sections 30 and seating valve 54 on top of the mandrel. The in side diameter of the tubing may, however, be too small to allow the packing element to expand to its maximum diameter. Pin 80 in that case moves down in slot 81. Compression spring 82, being weaker than compression spring 67, urges the packing element out against the inside surface of the tubing with a minor but substantially uniform force. The length of slot 81 is sufficient to accommodate the movement of lower packer element adapter 78 over a wide range of motion caused by variations in the inside diameter of the tubing and by wear on the outside surface of the packing element.

When the packing element has thus been diametrically expanded by pressure in the tubing, it completely packs off, or plugs, the tubing. The packer, together with the liquid in the tubing above it, may then be lifted to the surface by injecting gas below the packer as described in the above-mentioned co-pending joint application, S. N. 158,836. When the packer reaches the surface and the fluid head is displaced from the tubing, the body and mandrel are forced apart by spring 67, thereby axially elongating and decreasing the diameter of the packing element and unseating valve 54 so that the packer falls relatively freely through the tubing to a bottom stop or the like.

Manifestly, this invention which has been described by reference to specific examples is capable of a wide variety of modifications and uses, and such modifications and uses as may be construed to fall within the scope and meaning of the appended claims are also considered to be within the spirit and intent of this invention.

I claim:

1. A free piston adapted to move up and down in a tube comprising an expandable packer adapted to make a sliding seal with the inner wall of said tube, a passage within said packer for the flow of well fluids from one end of the free piston to the other, valve means for closing said passage and means operatively connecting said valve means and said packer to close said valve as said packer is expanded and to open said valve as said packer is contracted.

2. A free piston adapted to move up and down in a tube comprising means defining a pressure chamber ineluding a reciprocating member normally urged outward by fluid pressure within said chamber and normally urged inward by fluid pressure in said tube and outside of said pressure chamber, resilient means for urging said reciprocating member outward, an expansible packer adapted to be expanded, and means connecting said packer and reciprocating member whereby said packer is expanded responsive to inward movement of said reciprocating member and retracted responsive to outward movement of said reciprocating member.

3. The apparatus defined in claim 2 wherein there is provided a fluid passage inside said packer, a valve member'for closing said passage and a force transmitting connection between said valve and reciprocating members to move said valve member to open position when said reciprocating member moves outward.

4. As a subcombination, a free piston which comprises, in combination, a body member, a laterally expansible seal carried by said body member, a valve member movable with respect to said body member to close a flow passage communicating with the lower end of said body member, pressure responsive means having an operable connection with said valve member to move the same and having an effective area against which pressure can be applied to cause said valve member to move to closed position, said area being exposed to said passage intermediate said valve member and said lower end of said body member.

5. A gas lift plunger comprising a body, a tubular mandrel within said body, said tubular mandrel providing a fluid passage axially through said plunger, a piston on said mandrel, said mandrel and said piston forming with said body an enclosed pressure chamber, resilient means in said pressure chamber, the movement of said mandrel and said piston in said body to decrease the volume of said pressure chamber being resisted by said resilient means, valve means actuated by the movement of said mandrel in said body to close the fluid passage through said tubular mandrel, and a sleeve-type packing element, said packing element being connected at one end to said body and at the other end to said mandrel, the length of said packing element being decreased and the diameter of said packing element being expanded when the pressure on said plunger is increased and the Volume of said pressure chamber is reduced whereby said fluid passage is closed by said valve as said packing element is expanded. I

6. A gas lift plunger for raising a liquid through a conduit comprising an elongated body, an expansible packer to close the space between said body and the walls of said conduit, a tubular mandrel within said body, said tubular mandrel providing a fluid passage axially through said packer and at least a part of said body, said packer being connected at one end to said body and at the other end to said mandrel, valve means to close said fluid passage, and means to move said mandrel to close said valve means and simultaneously to expand said packer and to open said valve means and contract said packer.

7. A gas lift plunger according to claim 6 wherein said means to move said mandrel comprises means forming a pressure chamber within said body, a piston in said chamber forming a movable Wall in said chamber, resilient means within said pressure chamber acting on said piston to expand said chamber, means connecting said piston and said mandrel so that said mandrel is moved by said piston when said piston is moved due to variations in pressure on said chamber, said mandrel being moved by said piston compressing said resilient means to expand said packer and to close said valve means when the external pressure on said chamber is increased.

8. A gas lift plunger for lifting well fluids through a well tubing comprising an elongated body, an expansible packer to close the space between said body and said tubing, a tubular mandrel within said body and said packer, said tubular mandrel providing a fluid passage axially through said packer, said packer being connected at one end to said body and at the other end to said mandrel, valve means to close said fluid passage, means forming a pressure chamber within said body, a piston forming a movable wall in said chamber and being exposed to the pressure of said well fluids, resilient means including a gas in said pressure chamber acting on said piston to expand said chamber, and means connecting said piston and said mandrel so that said mandrel is moved by said piston when said piston is moved by variations in external pressure on said chamber, said piston being moved to compress said gas, expand said packer diametrically, and close said valve means when the external pressure on said chamber is increased.

9. A gas lift plunger for raising a liquid through a well tubing comprising an elongated body, a tubular packer connected at one end to said body, a tubular mandrel,

means connecting said tubular mandrel to the other end of said packer, said tubular mandrel providing a fluid passage axially through said packer, valve means to close said fluid passage, means forming a pressure chamber within said body, a piston forming a movable wall in said chamber and being exposed to the external pressure on said pressure chamber, resilient means including a compressible fluid in said pressure chamber acting on said piston to expand said chamber, and means connecting said piston and said mandrel so that said mandrel is moved by said piston when said piston is moved by variations in external pressure on said chamber, said piston being moved to compress said fluid, expand said packer diametrically, and close said valve means when the external pressure on said chamber is increased.

10. A gas lift plunger according to claim 9 including snap action means to restrain the movement of said mandrel until a predetermined external pressure change occurs on said chamber and then to release said mandrel to actuate substantially simultaneously said valve and said packer expansion, said mandrel being actuated to expand said packer diametrically and to close said valve due to an increase in external pressure on said chamber and to open said valve and contract said packer diametrically due to a decrease in external pressure on said chamber.

References Cited in the file of this patent UNITED STATES PATENTS 

